swing arm spindle oring leak

mk1 73 commando, with the bolt through the center of the spindle. after a short time the oil is leaking out at the inner oring seal.

I'm wondering if the oring and metal dust cover could be replace by the bigger swing arm pivot seal used on the mk3

Use 140 wt gear oil. Try Quad rings instead of O rings. Most important, shim to 0.005" thou for distance between gearbox/engine cradle and bronze bush/outer dust cover of swing-arm to reduce the amount of flex to help these poor old o rings/ x rings for doing their job. I use shims backing on outside of 06.0446 dust covers to get this gap. It still leaks some but less. I give it a squirt of 140 before I go on any distance rides.
Cheers,
Thomas

it was a tight fit the first time, so i will try the140wt first.

Get the gap fit prior to fitting the O/X rings in. shim to fit the 0.005 gap then put the O/X rings in after. Rubber has a tendency of making the feel... "feel"... tight.

FWIW, I believe the Mk3 o-ring and seal will fit. Only because my Mk2 came with them and I don't believe there was any modification to the cradle or swing arm. The outer seals for the Mk3 require a modified spindle as far as I know.

Long ago a read a post here from (member name deleted to protect the innocent) about using Amber Oil in the spindle and the speedo drive. It is perhaps one of the best bits of advice that has gone ignored by this forum.

http://www.jewellamberoil.com/

At each end of the interior spindle is a tiny hole about 1/16 that oil, not "grease" is supposed to be lucky enough to squeeze down through and provide some lube between the spindle and cradle.
Heinz Kegler told me that most everyone involved with Commandos back then agreed that only a lighter weight oil, like motor oil, could be trusted to get down those holes, but the factory was having lot of complaints about the oil dripping out from the end caps. So the factory decided it was better to specify a heavy oil like 140 weight in an effort to slow down, not completely stop, the leaking.
Heinz told me to squirt two cc's from a syringe of regular motor oil through the right hand end cap's little zerk fitting once a year, been doing so for over 25 years now.
Personally I would not use the amber oil as it is not a fluid but a grease that becomes a fluid but under heat so for the two reasons of the cradle and spindle getting hot enough to cause it to flow (made for hot rocker arms) and then guessing if it can get down the little spindle holes - not good enough, IMO

The idea of keeping it in place so it can work appeals. Like everything else you gotta decide for yourself. I'll report back next time I tear down the spindle. Probably another 20 years or so. Keep checking this space.